When moving mailboxes from Exchange 2016 to Exchange 2019 (on Windows 2022) I ran into a couple of StalledDueToTarget_Processor issues. These occur regularly and typically nothing to worry about, the move request will automatically continue in minutes.

Next I checked the task manager to see how performance of the Exchange servers were doing, and I noticed that the Disk Defragmenter was running. Processor utilization averaged around 20%, but it consumed also approx. 17GB of memory.

It turns out that the disk optimization is turned on by default on all disk in your server. When you select the properties of a disk, select the Tools tab and click Optimize you can see all disks, the scheduled optimization and the option to turn it off:

Disk optimization makes sense when you have a lot of sequential data or have an application that works with large chunks of data. Exchange server works with relatively small blocks of data and in a complete random order. So, disk optimization does not make sense on an Exchange server, and it is absolutely safe to turn it off on your Exchange server. This is alse mentioned in the Exchange Server storage configuration options article as a best practice. You don’t want to lose any valuable processor, disk and memory resources on a disk optimization process.

Thanks to reader Feras to supplying me the link to the configuration options.